The present invention is directed to a system for processing video signals in which bandwidth reduction thereof is accomplished by matching the information supplied to the human visual perception system to the capabilities of the human visual perception system to perceive the information.
The human visual perception system requires a considerable time to collect the image data needed to perceive fine details. This information is perceived by the fovea of the eye and requires many hundreds of microscopic eye movements before the content of the image can be recognized in fine detail. Thus, if rapid motion is occurring in a real time moving picture, information determining high resolution characteristics is not required. Although the peripheral vision or "coarse" vision aspect of the human visual perception system cannot perceive the detail content of an image, it can perceive very rapid movement and requires a high frame rate to avoid the perception of flicker.
Prior art systems for bandwidth reduction have constituted a frame of image data in the form of blocks or arrays of elements and performed two-dimensional transforms thereon to obtain blocks of components of various spatial frequencies. The information content of such a transformed frame of image data is then transmitted without regard to the ability of an human observer to perceive all the detail contained therein in the reconstitution of the frame of image data therefrom. Such prior art systems have been based on the transmission of all the data in a frame up to some resolution limit. Such systems have not provided enough bandwidth reduction without also producing of objectionable motion artifacts such as flicker.